22 Nov 2005
Thanksgiving is meant to be a time of giving thanks, of looking back at the year and seeing the big picture, of realizing that even though some things didn’t go as planned, overall there was a lot to be grateful for.
But around the globe this year humans have had a tough time. We have experienced devastating tsunamis, cataclysmic earthquakes, and a row of catastrophic hurricanes. “Without doubt this planet is unleashing its fury on us. And surely that is nothing to be thankful for.”
Let’s look deeper.
Most of this year’s natural disasters occur from surface phenomena. The earthquakes are the result of the great tectonic plates creeping across the face of the earth. And most tsunamis result from undersea shifts in these giant plates, with great ruptures displacing massive amounts of water. This disturbed water radiates out spreading the energy over huge areas sometimes with calamitous results.
Atmospheric phenomena like hurricanes and tornadoes can partially be attributed to the spinning of the earth. The spinning causes great movement in sea and air that combine to form the great lethal cyclones.
How can these characteristics of earth be anything to be thankful for? Well, I might argue for one that those great massive moving plates are actually a godsend to this planet.
They move because the planet underneath them is somewhat liquid-like. The great solid plates – like the North American Plate or the Pacific Plate – float and move about on this semi-liquid.
And this drifting about at just inches a year, which is not too fast, not too slow, gives us mountains and valleys and all the geographical array of surface features we see and enjoy and that promotes life’s profound diversity.
The plates are just thin enough that this can happen. Thicker and they wouldn’t be able to move and crack and the planet would eventually erode into a smooth sphere. Thinner and there would be an incessant parade of nasty volcanic explosions and destructive earthquakes all over the planet.
No other known planetary body has just the exactly right conditions for this amazing plate movement.
And the spin speed, covered in an earlier column, is just right, too. We spin faster and winds become devastating. Slower and the day-night temperature differences become unbearable.
And it is not just those several characteristics that cooperate to give us this Home of ours. The tilt, the distance from the sun, the type of star we orbit, the number of suns we have, our magnetic field, our extraordinary atmosphere, the amount of water on the earth and above it, our overall size and gravity, our nearly circular orbit, and many, many, many other characteristics make this a planet nonpareil.
But all these, as perfectly designed and coordinated as they are, don’t guarantee we won’t be without tragedy. For example, having so much life-giving water on this planet is an absolute blessing. But people may drown in it. Should we curse the water because of that? Obviously not. The same goes, in my opinion, for all the rest of the properties of this planet that leave a door open for disaster.
One challenge I have given my astronomy classes is to conceive of a planet more perfect for human life. I have not heard anyone ever give me anything that could be considered an improvement on what we have been given in Planet Earth.
Moreover, I might opine here that even in natural disasters there may be something to be thankful for. It is then that the best amongst us, the most courageous, the most heroic, come forward. There are few times when more people become more interested in selflessly helping those around them than when tragedy strikes. I don’t know about you, but observing unconditional love in the face of mass destruction makes me extremely thankful.
And it isn’t like we haven’t been warned. We can be very thankful for advances in modern technology that help us to see hurricanes coming, and determine when a volcano is about to blow, or tell us where earthquake faults may lie, or when to head for the hills as a tsunami approaches.
And it is hard not to blame ourselves for disobeying one of the basic maxims concerning the natural world around us. “Do not build your house on sand” is a simple, yet profoundly wise saying. Sand in itself is a great thing, but it is no place to build a house. And those of us who heed that warning suffer less when whatever disaster finally hits.
Need evidence? Compare the death tolls in countries with strict building codes against those with few or none when a big earthquake strikes. There is no comparison.
Yes, this year we have been hit with some high-profile calamities, to be sure. And we will get more next year, and the next. But we do live in the best imaginable place in the known universe.
And that is great reason to give thanks this Thanksgiving.
16 Nov 2005
Let’s focus on the sun this week!
Many of us look at the sun but few of us ask questions about it. Questions like: If it’s a ball of gas, why can’t we see through it? Where does all that heat come from? Is it really made of cheese? Oops! - wrong heavenly body.
Well, let’s start with where the energy source is. We know from experience that most hot things cool down when left alone by themselves. Take a red-hot poker out of the fire and set it aside and it cools down.
So why doesn’t the sun cool down? How does it stay hot? The same way you do. It has its own internal energy source. Only the sun doesn’t consume fuel to heat up, as we eat food and metabolize it. The sun fuses for its energy.
Way down deep inside, at the center of the sun called the core, the temperatures and pressures are intense to say the least. There, little hydrogen nuclei – the most prevalent element in the sun by far – get crammed so close together (high pressures) and move so fast (high temperatures) that they do things there that they would never dream of on earth.
These tiny little critters actually smash into each other and stick, in a series of events called fusion, producing helium as they do. But here’s the real important part: As they fuse, some of their mass turns into energy! I kid you not!
According to Einstein’s Special Theory of Relativity, mass and energy can be turned into each other. And that’s what’s happening in a fusion reaction, mass becomes energy.
The sun fuses about 600 million tons of hydrogen every second! About 4 million of those tons become pure energy. The rest becomes helium.
But the energy doesn’t now just have a free ride out of the sun, no siree bob!
Remember the pressure is intense, the atoms there are packed tight, so the newly formed energy- in the form of photons – doesn’t get far before being absorbed by some other particle. But not to worry! It gets re-emitted immediately in some random direction! But only to be reabsorbed again!
This process repeats itself countless times. The photon though, because of pressure differences, finds it easier to move gradually out towards the edge of the sun. But you’ll never believe how long it takes to reach there.
That lowly high-energy photon created way down in the core bounces about for millions of years until it finally gets its release papers!
This is why we cannot see through the sun. There is just too much stuff there absorbing light. But then why and when and where is the little packet of energy released???
If you could travel from the intensely hot, high-pressure core of the sun to its outer layers, you’d find the pressures getting lower and lower and lower. That means the “stuff” is packed less and less and less tightly.
A photon finally gets to a part of the sun where there is… nothing... blocking… its… path! Why, it suddenly finds that it is free to leave. And leave it does!
This release zone on the sun is called the photosphere. It is what we normally refer to as “the sun.” The big yellow ball we see up there is merely the first layer that allows light to flow out. There are actually layers above that – the chromosphere and the corona – but they are mostly invisible to our eyes except during an eclipse. And although those “invisible” layers are legitimate parts of the sun, for most of us “the sun” ends at the photosphere.
Now that the photon is free to leave it races out into space at about 186,000 miles a second.
Sadly some of these photons, after spending all that time making their way through the sun, break free, and just a little over 8 minutes of freedom later find themselves approaching a blue-green-white planet. They race through the atmosphere and in an instant are annihilated as they crash… onto your head.
The same thing happens in stars tens or hundreds of light years away. Their photons struggle to get through the stars. They finally break free, spend a couple hundred years racing through empty space, only to crash into the back of your eye, sending a message to your brain. And you elicit the response, “What a pretty star!”
C’est la vie, little photon.